The present invention relates to a control circuit for an electromagnetically driven programming shutter of a camera.
An electromagnetically driven programming shutter suffers from a large variation in its performance caused by the variation in the voltage or the current of the electric source energizing the shutter. Therefore, it has been the practice in the heretofore proposed electromagnetically driven programming shutter to provide a constant voltage circuit or a constant current circuit so as to prevent the variation in the performance of the shutter caused by the variation in the voltage or the current of the electric source energizing the shutter. However, the constant voltage circuit or the constant current circuit is very complex in construction and expensive to manufacture, while the voltage or the current supplied from such a constant voltage circuit or a constant current circuit is not used under the completely efficient conditions of the electric source but rather in a very low efficiency of the electric source in order to obtain the constant voltage or the constant current. Therefore, it is disadvantageous to use such a constant voltage circuit or a constant current circuit in an electromagnetically driven programming shutter requiring a rather large current.
On the other hand, an electromagnetically driven programming shutter suffers from a large variation in its performance caused by the variation in the temperature resulting in the variation of the voltage or the current supplied by the electric source to the shutter. Therefore, an expensive constant voltage circuit or an expensive constant current circuit has been required in the shutter in order to avoid the variation in the performance caused by the variation in the temperature. This has been a disadvantage in the heretofore proposed electromagnetically driven programming shutter.